"Dear Sirs," writes a correspondent from Stockholm, where sewers are called cloaks, "I take the liberty to write to you, since I from many sources have been informed that, for many years, a substantial number of krokodiles have found themselves a suitable athmosphere of living in the cloak tunnels of New York."

"Dear persons," begins the letter from a high school student in Wilkesboro, N.C. "Recently I have become very interested in a very uncommon subject, 'Alligator population in the New York City water system.'"

And a man from Celoron, N.Y., writes: "I disagree with a coworker whom insists that an alligator which had lived in a sewer system over a long period of time does not change color. I said I believe the pigmentation of the alligator would become much lighter and in some cases turn almost white." To all these Mr. Flaherty, a good-humored man with an alligator cigarette lighter on his desk, must reply, "No, Virginia, there are no alligators in the New York City sewer system."

In the "sewer game," as Mr. Flaherty calls it, which is not a glamour business, this has made John T. Flaherty something of a celebrity. There is even a makeshift star on his door, and a mock-up of a Variety headline that reads, "Flaherty says new alligator in sewer movie is a filmflam and is nothing but a croc."

Alligators are actually a very small part of Mr. Flaherty's business. His office, at 40 Worth Street, is filled with blueprints, and his mind is filled with capital or expense budget expenditure estimates. There are 6,500 miles of sewer lines in New York City, ranging from six-inch pipes to monster sewers big as a small band shell, from brick sewers circa 1840 to concrete structures under construction; these are Mr. Flaherty's daily concern.

He has worked as an engineer in this business for almost 30 years, and he has no disdain for it. Touring an underground chamber of brick and concrete near Starrett City in Brooklyn, damp and noisy with running water, he said, "A well-functioning sewer is a rather pleasant atmosphere--nice and cool in summertime, warm in the wintertime." In fact it seems just the place for an alligator, but in fact it is not.

Alligators have become Mr. Flaherty's sideline, and he handles them with flair. The myth is that travelers to Florida adopted the baby reptiles, tired of them and flushed them down the toilet and into the city sewer system, where they grew to immense size.

Perhaps a half-dozen people write to the city every year asking for particulars; once they got a very formal reply, but now they get Mr.Flaherty, who uses this opportunity to give vent to his creative impulses.

To a woman from Denver who asked if it was true that sewer workers carried guns in case of alligator attack: "As the resident expert on all matters relative to subterranean saurians, I can state with authority that there ain't no such animal. Rumors! How do they start? It is ironic, for instance, that you should write of sewer maintenance personnel here in New York carrying .38's to protect themselves from the ravages of rapacious reptiles. Did you know that there are many New Yorkers who believe that all residents of Denver carry .38's at all times?"

To the man from Stockholm, confirming that alligators have been adopted as pets: "I myself was bitten on the little finger of my right hand by one some 25 years ago in the stacks of the New York Public Library building. Please be reassured that the injury I suffered was quite minor, as the alligator in question was quite a little chap whose dentition was of the puniest."

And to the man from Celoron who thought alligators would pale below ground: "I could cite you many cogent, logical reasons why the sewer system is not a fit habitat for an alligator, but suffice it to say that, in the 28 years I have been in the sewer game, neither I nor any of the thousands of men who have worked to build, maintain or repair the sewer system has ever seen one, and a 10-foot, 800-pound alligator would be hard to miss. Of course, following the thought that you advance in your letter to its ultimate conclusion, perhaps the pigmentation affect has been so radical that they have been rendered invisible."

Mr. Flaherty says there are things living in the sewers, most of them rats. There are also insects and some stray fish; there once was a duck that got stuck in a pipe and flapped about wildly until it found a way out. There have been some bodies, and a few gangs that have set up subterranean sewer clubhouses.

There are, however, no alligators, because, Mr. Flaherty says, there is not enough space, there is not enough food--"the vast majority of it has been, to put it as delicately as possible, predigested"--and the torrents of water that run through the sewers during a heavy rain would drown even an alligator.

He adds that one clear proof of the absence of alligators is that not a single union official has ever advanced alligator infestation as a reason for a pay increase for sewer workers.

Mr. Flaherty says the biggest danger to him in the sewers is that the atmosphere steams his glasses. Mr. Flaherty says the biggest annoyance is not reptiles, but disposable diapers, which are improperly disposed of and so clog things up.

Mr. Flaherty says he is sorry to debunk such a wonderful myth. When a mercenary wrote to offer his services hunting alligators here, Mr. Flaherty suggested he write to the Mayor of Miami.

"Miami does have alligators in its sewers," Mr. Flaherty said with authority, knowing full well that someplace, someone is saying the selfsame thing about New York.

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